Fatal error: Uncaught Error: Interface "ILIAS\MetaData\OERHarvester\XML\WriterInterface" not found in /var/www/html/ilias/components/ILIAS/MetaData/classes/OERHarvester/XML/NullWriter.php:23 Stack trace: #0 {main} thrown in /var/www/html/ilias/components/ILIAS/MetaData/classes/OERHarvester/XML/NullWriter.php on line 23